The Beetle. 



This species is very easily distinguished from P. vandiiui by its 

 smaller size and somewhat darker color. The largest individuals are 

 smaller than the smallest of P. rundinei. In length the adult varies 

 from ]3 to 17 millimeters, in width from 7 to Si/o millimeters. The 

 average length is about five-eighths of an inch. 



The thorax of the beetle, in both sexes, is polished, rich mahogany 

 brown ; the elytra are somewhat paler, and polished in the female, 

 but covered with a very fine plumbeous pubescence in the male. The 

 species is very readily distinguished from P. vandinei by an examin- 

 ation of the genital organs of either male or female. The characters 

 by Avhich the two are separated are given in the table in the preceding 

 part of this paper, and are quite clearly shown in the plate. 



Life-History. 



This species has received more study in the immature stages than 

 any other, next to P. vandinei, due to its occurrence in the Guanica 

 district, where the South Coast Laboratory was located and where 

 most of the white-grub studies and experiments were conducted. 

 Prior to the work done by the writer, the presence of this species 

 in the Gruanica district as distinct from P. vandinei seems to have 

 been overlooked, as there is nothing in the earlier notes to indicate 

 that two species occurred together there, and no specimens of the 

 species were in the collection of the Experiment Station. 



The life-cycle agrees in a general way with those of the two pre- 

 ceding species in re([uiring one year. The immature stages require 

 approximately' nine months. 



For some unaccountable reason, while a large number of the 

 larvae, or grubs, of this ]\[ay-beetle were reared successfully to past 

 the middle of the third instar, only four individuals were successfully 

 reared to the adult. Two others successfully reached the pupal stage, 

 but a great majority died in the latter part of the third instar. "Most 

 of the fatalities occurred within a single week of the summer, and ii 

 is believed that the tin boxes, in which the grubs were being reared, 

 were allowed to become too hot from resting against a side of the 

 building exposed to the sun. 



Of the four individuals reared through from egg to adult, the 

 shortest required between 226 and 240 days and the longest between 

 321 and 331 days, which displays a range of duration of from eight 

 to eleven months. 



The average duration of the egg-to-adult period, obtained as a 



154 



